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ADS1291 Data errors

Other Parts Discussed in Thread: ADS1291

Hi e2e,

I'm using an ADS1291 in an application and am having some trouble. I am hoping for a second set of eyes. I am using 8ksps in continuous data read mode. My register settings are as follows:

  #define CONFIG1_SETTING         0x06
  #define CONFIG2_SETTING         0xE0
  #define LOFF_SETTING            0x11
  #define CH1SET_SETTING          0x60
  #define RLD_SENS_SETTING        0x00
  #define LOFF_SENS_SETTING       0x13
  #define LOFF_STAT_SETTING       0x1C
  #define RESP1_SETTING           0x02
  #define RESP2_SETTING           0x07
  #define GPIO_SETTING            0x0C

I use the start pin and pwm on my microcontroller in order to sample data over a very precise time. I have the DRDY pin connected to an external interrupt so most of my process is done in the background. The trouble I'm having is that I am seeing data that doesn't make sense coming back. I am consistently getting 0xFEFxxx (i.e., only the three least significant nibbles ever change) despite my using several test voltages ( all less than .2 V to avoid saturating the amplifier). I will also swap inputs and still get the same value when I would expect to see an equal magnitude reading multiplied by -1. Is this a problem anyone else has encountered or has ideas about?

Thanks,

Don

  • Hi Don,

    Sorry for the delayed reply. Have you figured this out?

    If you still need some help, could you please share a scope capture showing the input waveform and the resulting digital outputs?

    It sounds like you are correctly limiting the differential signal amplitude based on the selected gain of PGA = 12. What is the common-mode of your input signal? Could either the INP or INN inputs be too close to the supply rails?

    Let me know how I may help you with this.

    Best Regards,